Crimp with an insert to hold a cable

ABSTRACT

An apparatus for securing a cerclage member about a bone within a living body comprises a crimp including a first space extending longitudinally therethrough from a first space proximal opening to a first space distal opening, the first space sized and shaped to slidably receive a cerclage member therein and a second space extending parallel to the first space from a second space proximal opening to a second space distal opening, the second space including a proximal portion to receive the cerclage member and a distal portion decreasing in cross-sectional area and an insert that, when inserted into the second space distal opening adjacent to a cerclage member, a decreasing cross-sectional area of the second space distal portion forces the insert laterally relative to a longitudinal axis of the second space, pinching and locking the cerclage member against movement relative to the crimp.

PRIORITY CLAIM

The present application is a Continuation Application of U.S. patentapplication Ser. No. 13/002,621 filed on Jan. 4, 2011, which is a 371application of PCT Patent Application Serial No. PCT/US2008/082462 filedon Nov. 5, 2008, which claims the priority to U.S. ProvisionalApplication Ser. No. 61/084,289 filed on Jul. 29, 2008. The entiredisclosures of these patents/applications are expressly incorporatedherein by reference.

FIELD OF THE INVENTION

The invention relates generally to surgical methods and apparatus fortreating bones and more particularly relates to a method and apparatusfor bone fixation using cable for a bone cerclage technique.

BACKGROUND INFORMATION

The treatment of bones often involves a bone cerclage technique whereina wire or other cable is used to aid bone fixation or repair. Bonecerclage procedures generally require that a wire or cable be loopedaround the bone and secured tightly. Present bone cerclage devices andmethods require at least one incision adjacent the target portion ofbone large enough to permit the insertion of bone cerclage tools used toinsert and secure the cable around the bone.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus for securing acerclage member about a bone within a living body comprising a crimpincluding a first space extending longitudinally therethrough from afirst space proximal opening to a first space distal opening, the firstspace sized and shaped to slidably receive a cerclage member therein anda second space extending substantially parallel to the first space froma second space proximal opening to a second space distal opening, thesecond space including a proximal portion sized and shaped to slidablyreceive the cerclage member therein and a distal portion decreasing incross-sectional area from the second space distal opening to theproximal portion and an insert sized and shaped so that, when insertedinto the second space distal opening adjacent to a cerclage memberinserted therethrough, the decreasing cross-sectional area of the secondspace distal portion forces the insert laterally relative to alongitudinal axis of the second space pinching the cerclage member andlocking the cerclage member against movement relative to the crimp.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a perspective view of a crimp according to a firstembodiment of the invention;

FIG. 2 shows a perspective view of an insert to be used with the crimpof FIG. 1;

FIG. 3 shows a partial cross-sectional view of the crimp of FIG. 1 in anunlocked configuration;

FIG. 4 shows a partial cross-sectional view of the crimp of FIG. 1 in alocked configuration;

FIG. 5 shows a perspective view of a crimp according to a secondembodiment of the invention;

FIG. 6 shows a partial cross-sectional view of the crimp of FIG. 5 in anunlocked configuration;

FIG. 7 shows a partial cross-sectional view of the crimp of FIG. 5 in alocked configuration;

FIG. 8 shows a perspective view of a crimp according to a thirdembodiment of the invention;

FIG. 9 shows a perspective view of an insert to be used with the crimpof FIG. 8;

FIG. 10 shows a partial cross-sectional view of the crimp of FIG. 8 inan unlocked configuration; and

FIG. 11 shows a partial cross-sectional view of the crimp of FIG. 8 in alocked configuration.

DETAILED DESCRIPTION

The present invention may be further understood with reference to thefollowing description and the appended drawings, wherein like elementsare referred to with the same reference numerals. The present inventionrelates generally to methods and devices for the stabilization andfixation of fractured bones and bone fragments via bone cerclage.Specifically, the present invention relates to methods and devices forsecuring a cerclage wire or cable in a desired position looped around atarget portion of bone. Embodiments of the present invention may also beemployed with any of a plurality of bone treatment procedures requiringa bone cerclage. As used in this application, the terms proximal anddistal refer to direction along the cerclage cable with a first end ofthe cable being identified as the proximal end and a second end of thecable being identified as distal. Components of the crimp will then bedescribed in relation to the direction in which the cable passestherethrough. For example, an opening to a lumen into which a distal endof the cable is inserted and against which a proximal end of the cableis held will be described as the proximal opening of the lumen. Theopposite end of the lumen from which the distal end of the cable exitswill be described as the distal opening of the lumen and the otherelements of the crimp will be similarly identified.

As shown in FIGS. 1-4, a crimping device 100 according to a firstexemplary embodiment of the invention comprises a crimp 102 forreceiving a cable 10 to be looped around a target portion of a bone (notshown). The crimp 102 comprises a cable lumen 108 and a crimp lumen 118extending substantially parallel to one another along a longitudinallength of the crimp 102. As described in more detail below, the distalend of a cable 10 is inserted into the cable lumen 108 via a proximalopening 114 thereof until an enlarged proximal end 12 thereof engagesthe portion of the crimp 102 surrounding the opening 114 preventing thecable 10 from being drawn further into the lumen 108. The distal end ofthe cable 10 is then drawn from a distal opening 112 of the lumen 108and looped around the bone to return to the crimp 102. The distal end ofthe cable 10 is then inserted into the crimp lumen 118 via a proximalopening 124 until it passes out of the crimp lumen 118 via a distalopening 122 on the opposite side of the crimp 102. An insert 126 is thenplaced over the distal end of the cable 10 and slid along the cable 10until it enters the distal opening 122. As described in more detailbelow, the crimp lumen 118 is tapered with a diameter thereof decreasingfrom a maximum at the distal opening 122 to a minimum proximallythereof. After the cable 10 has been tensioned to a desired level, theinsert 126 is forced proximally into the tapered distal portion of thecrimp lumen 118 so that the inward taper of the distal portion of thecrimp lumen 118 exerts radially inwardly directed force against theinsert 126 which increases as the insert is forced further into thecrimp lumen 118. This force crushes the insert 126 against the cable 10locking it in place over the cable 10 and preventing the cable 10 frommoving proximally out of the opening 124. This locks the cable 10 in thedesired position around the bone and maintains the desired tension onthe cable 10. A proximal portion of the insert 126 may, for example, besized and shaped to frictionally engage the tapered portion of the crimplumen 118. However, those skilled in the art will understand that thetension of the cable 10 will draw the insert 126 further into the crimplumen 118 securing it therein.

The crimp 102 may be formed of any suitable biocompatible material aswould be understood by those skilled in the art so long as this materialexhibits rigidity sufficient to withstand the forces applied theretowhen deployed in the body. Exemplary materials for the crimp 102 andinsert 126 include, but are not limited to, stainless steel, titanium,titanium alloys, Polyetheretherketone (“PEEK”) or any combinationthereof. As would be understood by those skilled in the art, the cablelumen 108 is formed with a size and shape permitting the selectiveinsertion of the cable 10 therethrough with, for example, asubstantially uniform diameter D₁ slightly greater than an outerdiameter of the cable 10. In an exemplary embodiment, the lumen 108 issubstantially circular. It is noted, that the cross-section of the cablelumen 108 may comprise any shape suited to a shape of the cable 10. Thecrimp lumen 118 extends longitudinally from a proximal end 122 to adistal end 124 and is separated from the cable lumen 108 along a distalface 104 of the crimp 102 by a desired distance which may, for example,be selected to minimize the size of the crimp 102 while maintaining thestructural integrity thereof. The crimp lumen 118 may for example, besubstantially circular in cross-section, tapering from a diameter D₂ atthe distal opening 122 to a diameter D₁ at a taper end point 116 locatedat any desired point within the crimp lumen 118. In one embodiment, thetaper end point 116 is located midway between the distal opening 122 andthe proximal opening 124. Alternatively, the taper end point 116 may belocated at any point enabling the insert 126 to be suitable crushedagainst the cable 10, as will be described in greater detailhereinafter. The remainder of the crimp lumen 118 located distally ofthe taper end point 116 may comprise a uniform diameter D₁. Furthermore,those skilled in the art will understand that the diameter D₁ of thecrimp lumen 118 may be substantially equal to the diameter D₁ of thecable lumen 108 as it will accommodate the same cable 10. However, thisis not necessary and the diameter D₁ may be any value sufficient toreceive the cable 10 and small enough to prevent the passage of theinsert 126 proximally therethrough.

The insert 126 according to the first embodiment of the presentinvention is formed as an elongated nail extending from an increaseddiameter head 128 at a distal end thereof to a slotted shaft 130 at aproximal end. Specifically, a plurality of arms 132 spaced from oneanother circumferentially by a plurality of slots 134 extendingproximally from the head 128 in a substantially cylindricalconfiguration defining a lumen 136 which extends through the insert 126from a distal opening 138 to a proximal opening 140. The lumen 136 issized and shaped to slidably receive the cable 10 therethrough and, inan exemplary embodiment, has a diameter D₁ sufficient to slidablyreceive the cable 10 therethrough. A diameter of the head 128 may bemade greater than a diameter D₂ of the proximal end 122 of the crimplumen 118 to prevent insertion of the insert 126 thereinto beyond apredetermined distance. However, this is not necessary as the taperedportion of the crimp lumen 118 and the proximal portion of the crimplumen 118 will be selected to prevent the passage of the insert 126therethrough.

FIGS. 3-4 sequentially depict the process by which the cable 10 islocked onto the crimp 102 in accordance with a first exemplary method ofthe present invention. Initially, the distal end of the cable 10 isinserted into the cable lumen 108 via the distal opening 114 until theenlarged proximal end 12 of the cable 10 prevents the cable 10 frombeing further inserted thereinto. Engagement of the enlarged proximalend 12 with the distal face 106 locks the distal end of the cable 10against the crimp 102. The cable 10 is then drawn out of the cable lumen108 via the distal opening 112 and looped around the bone in a desiredposition. After being looped around the bone, the distal end of thecable 10 is inserted into the crimp lumen 118 via the proximal opening124 and passed therethrough to exit via the distal opening 122. Thedistal end of the cable 10 is then inserted into the lumen 136 of theinsert via the distal opening 138 and the insert 126 is slid proximallyover the cable 10. Tension may then be applied to the cable 10 until adesired level of tension is obtained and the insert 126 is slidproximally over the cable 10 until a proximal end of the insert 126enters the distal opening 122 of the crimp lumen 118, as shown in FIG.3. It is noted that, in the position shown in FIG. 3, radiallyconstrictive pressure has not yet been applied to the arms 132 which arenot yet deflected radially inward. Alternatively, the insert 126 may beassembled within the distal opening 122 of the crimp lumen 118 in theposition of FIG. 3 in the factory so that a user may thread the cable 10through the crimp lumen 118 and the lumen 136 of the insert 126 in asingle step. For example, the insert 126 may be held in this positionthrough a friction fit between the proximal end of the insert 126 andthe distal end of the crimp lumen 118. As the proximal end of the insert126 is not yet pinched radially inward in this configuration, the cable10 passes easily through the lumen 136. The insert 126 may then bedriven the desired distance into the crimp lumen 118 during thetensioning process. That is, the tensioning mechanism (not shown) may beabutted against the distal head 128 of the insert 126 so that, astension on the cable 10 is increased, the tensioning mechanism appliesincreasing proximally directed force against the insert 126 forcing theinsert 126 into the crimp lumen 118 to force the arms 130 radiallyinward into the lumen 136 pinching the cable 10 and locking the cable 10in the desired position at the desired tension, as shown in FIG. 4. Aswould be understood by those skilled in the art, this radially inwardforce may deform pinched portion of the cable 10 further aiding inlocking the cable 10 in the desired position within the crimp 102.

The crimp lumen 118 may be formed in any desired size and shape as wouldbe understood by those skilled in the art. As shown in FIGS. 5-7, acrimp 202 according to a further embodiment of the invention includes adistal end 222 of a crimp lumen 218 having a substantially D-shapedcross section. Specifically, a cross section of the distal portion ofthe crimp lumen 218 comprises a substantially planar wall 220 connectedto an arched portion 210. A distal portion 218′ of the crimp lumen 218tapers down in size from a maximum at the distal opening 222 to a taperend point 216. A distal portion 218″ of the crimp lumen 218 locatedproximally of the taper end point 216 has a substantially circular crosssection similar to the crimp lumen 118 of FIGS. 1-4. A cable lumen 208extends longitudinally through the crimp 202, substantially parallel tothe crimp lumen 218. As described earlier with respect to FIGS. 1-4, adiameter D₁ of the cable lumen 208 and the proximal portion 218″ of thecrimp lumen 218 may be substantially equivalent to an outer diameter ofthe cable 10.

As would be understood by those skilled in the art, an exemplary insert226 for use with the crimp 202 is sized and shaped to be inserted intothe distal portion 218′ of the crimp lumen 218 and to be forced by thetapered shape thereof to apply a radially inward locking pressureagainst the cable 10 when driven into the distal portion 218′ of thecrimp lumen 218. The insert 226 is formed as a nail including anincreased diameter head 228 extending radially outward from a distal endthereof and an elongated shaft 230 extending proximally from the head228. The shaft 230 may be formed as a substantially rectangular elementwith a thickness selected to reside easily beside the cable 10 withinthe distal opening 222 but which, when driven proximally into thetapered distal portion 218′, will be compressed against the cable 10applying an increasing lateral force thereto until a desired lockingposition of the insert 226 is reached. Specifically, the head 228projects laterally from the insert 226 on a side thereof which facesaway from the cable 10 (i.e., away from the arched side of the opening222). A proximal surface of the head 228 is tapered at an angle ⊖₁substantially equivalent to a taper angle ⊖₂ of the wall 220 so that,when the insert 226 is fully inserted into the crimp lumen 218 and asurface of the shaft 230 has been pushed against the tapered surface ofthe crimp lumen 218, the tapered proximal surface of the head 228 liessubstantially flush against a distal face 204 of the crimp 202, as thoseskilled in the art will understand. Furthermore, engagement of the head228 with the proximal face 204 prevents insertion of the insert 226 intothe crimp lumen 218 beyond a desired predetermined distance. When inthis position, as can be seen in FIG. 7, the proximal end of the shaft230 has pinched the cable 10 and compressed an adjacent surface thereoflocking the cable 10 in the desired position and maintaining the desiredtension thereon.

FIGS. 6-7 sequentially depict the process by which the cable 10 islocked onto the crimp 202. In a manner similar to that described abovefor the crimp 102, a distal end of the cable 10 is inserted into thecable lumen 208 via the proximal opening 214 until the enlarged proximalend 12 engages a proximal face 206 of the crimp 202. At this point, thedistal end of the cable 10 has passed out of the cable lumen 208 via thedistal opening 212. The cable 10 is then looped around the bone in atarget position and the distal end of the cable is inserted into thecrimp lumen 218 via the proximal opening 224. The cable 10 is passedthrough the crimp lumen 218 to exit therefrom via the distal opening222. The distal end of the cable 10 is then coupled to any knowntensioning mechanism (not shown) as would be understood by those skilledin the art and the insert 226 is inserted into the distal opening 222adjacent to the cable 10 as shown in FIG. 6. The tensioning mechanismmay then be actuated to increase the tension on the cable 10 until adesired level has been reached. As described above in regard to thecrimp 102, the tensioning mechanism may be abutted against the insert226 so that, as the cable 10 is tensioned to the desired level, thetensioning mechanism may force the insert 226 into the crimp lumen 218until the cable 10 has been locked in position at the desired tension asshown in FIG. 7.

As shown in FIGS. 8-11, a crimp 302 according to another embodiment ofthe invention, includes a single lumen 318 extending longitudinallytherethrough from a proximal end 324 to a proximal end 324. The lumen318 is formed with a oblong cross-section and maintains a substantiallyuniform cross-sectional area. An insert 310 received within the lumen318 includes sides which, in an initial configuration, are spaced fromeach of the lateral edges of the lumen 318 by spaces 326 and 328 sizedto permit the cable 10 to pass through the lumen 318 on either side ofthe insert 310 as shown in FIG. 10. As would be understood by thoseskilled in the art, at least one of the proximal and distal openings324, 322, respectively, of the lumen 318 may be made slightly smallerthan a cross-sectional area of the insert 310 to prevent the insert 310from passing therethrough. The insert 310 is substantially U-shaped witha longitudinal length less than that of the crimp 302. Specifically, theinsert 310 comprises a pair of substantially parallel arms 312 extendingdistally from a proximal joint 314 and separated from one another by aspace 315. A distal end 316 of each of the arms 312 is expanded toproject into the space 315 forming a narrow entrance to the space 315 atthe distal end thereof. A proximal end of the space 1315 forms a groove308 which as described in more detail below, is sized and shaped toreceive the proximal end of a wedge member 330 which is inserted intothe space 315 to lock the cable within the crimp 302.

The wedge member 330 is substantially triangular with a proximal endformed as a plug 334 which may, for example, be substantiallycylindrical, which is sized and shaped to be received in the groove 308.The plug 334 is also sized so that it may be slid between the distalends 316 of the arms 312 to force the arms from the initialconfiguration shown in FIGS. 8 and 10 to the locking configuration shownin FIG. 11. Specifically, after the cable 10 has been passed through thespace 326 of the lumen 318, looped around the bone and passed throughthe space 328 on the opposite side of the lumen 318 and tensioned asdesired as will be described in more detail below, the wedge member 330is driven into the insert 310 with the plug 334 sliding between thedistal ends 316 of the arms 312, the tapered sides of the wedge member330 force the arms 312 further from each other so that lateral sidesthereof are forced into the spaces 326 and 328 driving the cable 10against the walls of the lumen 318 and locking the cable 310 in positionwhile maintaining the desired tension thereon. That is, as the width ofthe wedge member 330 increases from the proximal end to the distal end,the further proximally the wedge is driven into the space 315, thefurther the distal ends 316 of the arms 312 are driven laterally from,one another urging the laterally outer sides of the arms 312 intocontact with the cable 10 locking both the proximal and distal portionsthereof against the walls of the lumen 318 in the spaces 326 and 328.

In use, a distal end of a cable 10 which in this embodiment may or maynot include an enlarged proximal end, is inserted into the space 326 ofthe lumen 318 via the proximal opening 324 to exit the crimp 302 via thedistal opening 322. The cable 10 is then looped around the bone along adesired path and reinserted into the crimp 302 via the opening 324. Thistime the distal end of the cable is passed through the space 328 to exitthe distal opening 322 and connected to a tensioning mechanism. When thedesired tension has been applied to the cable 10, the wedge member 330is driven into the space 315 by applying a proximally directed force toa distal end 332 thereof until the plug 334 is seated in the groove 308locking the cable 10 to the crimp 302 in the desired position and withthe desired tension.

It will be apparent to those skilled in the art that variousmodifications and variations may be made in the structure and themethodology of the present invention, without departing from the spiritor scope of the invention. Thus, it is intended that the presentinvention cover modifications and variations of the invention providedthat they come within the scope of the appended claims and theirequivalents.

What is claimed is:
 1. An apparatus for securing a cerclage member abouta bone within a living body, comprising: a crimp including a first spaceextending longitudinally therethrough from a first space proximalopening to a first space distal opening, the first space being acylinder sized and shaped to slidably receive a cerclage member therein,the crimp including a second space extending substantially parallel tothe first space, the second space including a proximal portion and adistal portion extending distally from the proximal portion, theproximal portion being cylindrical and extending from a proximal portionproximal opening to a proximal portion distal end open to a proximal endof the distal portion, the distal portion extending from the distalportion proximal end to a distal portion distal opening and beingtapered to increase in cross-sectional area from the distal portionproximal end to the distal portion distal opening; and an insert sizedand shaped so that, when inserted into the distal portion via the distalportion distal opening adjacent to the cerclage member insertedtherethrough, the tapering of the distal portion forces the insertlaterally relative to a longitudinal axis of the second space pinchingthe cerclage member at a pinching point where the cerclage member has adecreased cross sectional size and locking the cerclage member againstmovement relative to the crimp.
 2. The apparatus of claim 1, wherein thefirst space and the second space are formed as separate lumens separatedfrom one another by a wall.
 3. The apparatus of claim 1, wherein theinsert includes a lumen sized and shaped to slidably receive thecerclage member therein, the lumen being collapsed as the insert isforced into the distal portion of the second space to pinch the cerclagemember within the lumen of the insert.
 4. The apparatus of claim 3,wherein the insert comprises a plurality of arms projecting proximallytherefrom surrounding the lumen of the insert, the arms being separatedfrom one another circumferentially by a plurality of slots extendinglongitudinally through the insert.
 5. The apparatus of claim 3, whereina cross section of the insert is substantially circular.
 6. Theapparatus of claim 1, wherein the insert is formed as a shaft shaped tobe inserted on one side of the cerclage member to pinch the cerclagemember between a proximal end of the insert and a wall of the secondspace as the insert is forced into the distal portion distal opening. 7.The apparatus of claim 1, wherein the distal portion distal opening andthe distal portion proximal end are substantially circular.
 8. Theapparatus of claim 7, wherein the distal portion proximal end has afirst diameter and the distal portion distal opening has a seconddiameter greater than the first diameter.
 9. The apparatus of claim 1,wherein the distal portion distal opening and the distal portionproximal end are non-circular.
 10. The apparatus of claim 9, wherein thedistal portion distal opening and the distal portion proximal end aresubstantially D-shaped with a first rounded side shaped to correspond toa shape of the cerclage member and a second side opposite the first sideshaped to slidably receive the insert.
 11. The apparatus of claim 10,wherein the first rounded side is substantially parallel to thelongitudinal axis of the second space while the second side intersectsthe longitudinal axis of the second space at a predetermined taperangle.
 12. The apparatus of claim 11, wherein the insert furthercomprises a head projecting laterally from a distal end of the insert.13. The apparatus of claim 12, wherein a proximal face of the head ofthe insert is formed in a plane intersecting a plane perpendicular tothe longitudinal axis of the second space at an angle substantiallyequal to the taper angle.
 14. A method for treating a bone within aliving body, comprising: positioning a crimp at a desired positionadjacent to a bone to be treated; inserting a distal end of a loop ofcable into a first space extending longitudinally through the crimp viaa first space proximal opening thereof, the first space being acylinder; drawing the distal end of the cable from a first space distalopening of the first space and looping the cable around a target portionof bone to be treated; after looping the cable around the target portionof bone, passing the cable through the crimp via a second spaceextending longitudinally therethrough substantially parallel to thefirst space, the second space including a proximal portion and a distalportion extending distally from the proximal portion, the proximalportion being cylindrical and extending from a proximal portion proximalopening to a proximal portion distal end open to a proximal end of thedistal portion, the distal portion extending from the distal portionproximal end to a distal portion distal opening, the cable beinginserted into the second space via the distal portion distal opening,the distal portion being tapered to increase in cross-sectional areafrom the distal portion proximal end to the distal portion distalopening; placing a desired tension on the cable; and driving an insertinto the distal portion of the second space via the distal portiondistal opening to secure the cable within the second space maintainingthe desired tension thereon, the tapering of the distal portion forcingthe insert laterally relative to a longitudinal axis of the second spacepinching the cerclage member and locking the cerclage member againstmovement relative to the crimp.
 15. An apparatus for securing a cerclagemember about a bone within a living body, the apparatus comprising: acrimp including a lumen extending longitudinally therethrough from aproximal opening to a distal opening; and an insert received within thelumen, the insert being sized and shaped so that, when in an initialconfiguration, lateral sides thereof extend substantially parallel towalls of the lumen forming a first space on a first side of the insertsized to slidably receive therein a cerclage member to be bound around atarget portion of bone and forming, on a second side of the lumen asecond space sized to slidably receive the cerclage member, the insertincluding a void between the first and second sides thereof and anopening to the void at a distal end of the insert; and a wedge memberincluding a reduced width proximal end and sized to be received withinthe opening at the distal end of the insert, a width of the wedge membertapering from the reduced width proximal end to a maximum width distallytherefrom, the wedge member being sized so that, when driven into thevoid via the opening at the distal end of the insert, the taper of thewedge member drives the first and second sides of the insert laterallyoutward into the first and second spaces to secure the cerclage membertherein, wherein the insert includes a cylindrical groove at a proximalend of the void and extending along a longitudinal axis perpendicular toa longitudinal axis of the insert, and the wedge member includes acylindrical plug at a proximal end thereof extending along alongitudinal axis perpendicular to a longitudinal axis of the wedge, thegroove being sized and shaped to receive the plug when the wedge memberis inserted into the void in a desired configuration in response to alongitudinally directed force.
 16. The apparatus of claim 15, whereinthe insert is substantially U-shaped with the first and second armsconnected to one another via a joint at a proximal end thereof.
 17. Theapparatus of claim 15, wherein distal ends of the first and second armsof the insert include projections extending laterally inward toward oneanother and separated by one another by a width less than a width of thevoid.